The invention relates to a face mask, more particularly, a helmet type face mask adapted to be used in cold environments for protecting the wearer's face from the cold, as well as providing warm air to the wearer, or in dusty or other environments contaminated with airborne particulate matter for protecting the face and eyes and providing clean air to the wearer.
In the past, there have been disclosed many face masks for various purposes. However, such face masks, even if designed for cold environments, are not fully satisfactory.
In U.S. Pat. No. 1,262,566, there is disclosed a tunnel mask, which comprises outer and inner walls covering the head of the wearer, openings within the walls covered with glass, an inlet port at the outer wall from which an air supply pipe extends outwardly, and outlet ports provided at the inner wall. When air is inhaled, air enters the interior of the mask through the air supply pipe, the inlet port and the outlet ports. Then, the air is exhaled to the atmosphere out of the bottom of the mask. Since the mask does not sealingly cover the head of the wearer, the mask is not suitable for cold environments and environments contaminated with airborne particulate matter.
A portable respiratory apparatus is disclosed in U.S. Pat. No. 3,902,486. The apparatus comprises a body including inlet and outlet valves, a mask secured to the body and a conduit connected to the inlet valve of the body. When air is inhaled, air enters the mask through the conduit and the inlet valve, whereas the outlet valve closes. While, in case of exhalation of the air, the inlet valve closes and the air flows out through the outlet valve. A lower end of the conduit can be carried in clothing of the user. However, in a cold environment, inspired air is directly exhaled to the atmosphere through the outlet valve; therefore, the outlet valve may not properly operate due to freezing on the outlet valve of moisture contained in the exhaled air.
Therefore, an object of the invention is to provide a face mask adapted for use in cold environments as well as in environments contaminated with airborne particulate matter.
Another object of the invention is to provide a face mask, in which the field of view of the face mask is kept clear.
A further object of the invention is to provide a face mask which is light and easily worn by the user.
Still further objects and advantages of the invention will be apparent from the following description.